By “communication equipment” one means here any equipment, mobile or not, adapted to receive and/or transmit RF signals to and/or from mobile (or cellular) and/or WLAN and/or broadcast and/or positioning networks, and notably a mobile phone (for instance a GSM/GPRS, UMTS or WiMax mobile phone), a personal digital assistant (PDA), a laptop, a PCMCIA card (giving a communication functionality to an equipment), a USB dongle (for use in computers and their peripherals), a satellite positioning device (for instance a GPS one), or a microwave receiver for radars (collision avoidance car radars, for instance), a television receiver, a RFID (RF IDentifier) device, or a NFC (Near Field Communication) device.
Moreover, by “antenna device” one means here a device comprising a substrate, a planar antenna element, and at least a passive component (for instance a LC matching filter and/or decoupling capacitor(s)) and/or at least an active component (for instance a low noise receiver) connected to the antenna element through connecting means.
When an antenna device is intended for working at very high frequency, its (radiating) antenna element may have dimensions in the order of few millimeters (typically a quarter of the working wavelength). So, the antenna element can be fixed to, or integrated into, a carrier which can be a semiconductor or semi-insulating substrate. Unfortunately, when the antenna element is working it induces electromagnetic disturbances which are harmful to the working of the active and/or passive components that are in its vicinity. Therefore, the antenna element and the active and/or passive components must be spaced apart at a distance which renders the antenna electromagnetic disturbances negligible. Consequently, the antenna device is bulky and its antenna element and the associated electronic complex function(s) cannot be integrated into the same carrier.
It has been recently proposed to integrate an antenna element of the quasi-Yagi type and some associated integrated components on top of the same side of a low resistivity silicon multilayer substrate. The integrated components are partly separated from the antenna by a truncated layer which is defined in the substrate and is connected to the antenna element. Such a solution is described in the document of Zhang Y. P. “Recent advances in integration of antennas on silicon chip and on ceramic package”, CONF-2005 IEEE International Workshop on Antenna Technology: Small Antennas and Novel Metamaterials, 7-9 Mar. 2005—Singapore, IEEE Piscataway, N.J., USA. This solution allows partial isolation of some components from the antenna radiations. But, it requires a complex and expensive process which is not adapted to manufacturing of chips and antennas that are commonly used in consumer equipments. Moreover, only one face of the carrier (or substrate) is used. So there is no possibility to get a real miniaturised integrated antenna device except if the carrier (or substrate) dimensions are very large.